Foreign object damage elimination system

ABSTRACT

An assembly configured to prevent damage to an object during manufacture thereof is provided including a first housing having a substantially hollow interior. An exposed first planar surface of the first housing includes an inlet port and a plurality of small openings formed about the periphery. The inlet port, the hollow interior, and the plurality of small openings form a fluid flow path through the assembly. A second housing similar in size and shape to the first housing, has an exposed second planar surface. An intermediate layer is arranged between the first housing and the second housing. A cross-section of the intermediate layer is configured to change shape in response to a compression force applied thereto by the first housing and the second housing to form a seal separating an exterior portion of the objection exposed to the plurality of small openings from an interior surface of the object.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a Divisional of U.S. patent application Ser. No.15/327,565, filed Jan. 19, 2017, which is a U.S. National Stageapplication of PCT/US2015/041092, filed Jul. 20, 2015, which claims thebenefit of U.S. Provisional Application No. 62/027,594, filed Jul. 22,2014, the contents of which are incorporated by reference in theirentirety herein.

BACKGROUND OF THE INVENTION

Exemplary embodiments of the invention relate to a rotary wing aircraft,and more particularly, to a method and apparatus for manufacturing arotor blade of a rotary wing aircraft.

During fabrication of a rotor blade of a rotary wing aircraft, debrissuch as titanium and stainless steel splinters or chips can enter theblade spar and become trapped in the closed tip of the blade. Inaddition, these chips can become wedged between the conic and flatportions of the interior spar surface causing damage, such as scratchesfor example, to a critical area of the spar.

BRIEF DESCRIPTION OF THE INVENTION

According to one embodiment of the invention, an assembly configured toprevent damage to an object during manufacture thereof is providedincluding a first housing having a substantially hollow interior. Anexposed first planar surface of the first housing includes an inlet portand a plurality of small openings formed about the periphery. The inletport, the hollow interior, and the plurality of small openings form afluid flow path through the assembly. A second housing, substantiallysimilar in size and shape to the first housing, has an exposed secondplanar surface. An intermediate layer is arranged between the firsthousing and the second housing. A cross-section of the intermediatelayer is configured to change shape in response to a compression forceapplied thereto by the first housing and the second housing to form aseal separating an exterior portion of the objection exposed to theplurality of small openings from an interior surface of the object.

In addition to one or more of the features described above, or as analternative, in further embodiments the flow path is configured tocounter a flow of debris into the interior surface of the object.

In addition to one or more of the features described above, or as analternative, in further embodiments the inlet port is connected to apump operably coupled to a fluid supply.

In addition to one or more of the features described above, or as analternative, in further embodiments the fluid supply includes one of airor coolant.

In addition to one or more of the features described above, or as analternative, in further embodiments the plurality of small openings isequidistantly spaced about the periphery of the first planar surface.

In addition to one or more of the features described above, or as analternative, in further embodiments a portion of the plurality of smallopenings has a diameter larger than a remainder of the plurality ofsmall openings.

In addition to one or more of the features described above, or as analternative, in further embodiments the portion of small openingsadjacent the inlet port have a smaller diameter than the remainder ofthe plurality of small openings.

In addition to one or more of the features described above, or as analternative, in further embodiments at least one fastener extendsthrough and is configured to affix the first housing, the intermediatelayer, and the second housing.

In addition to one or more of the features described above, or as analternative, in further embodiments a compression fastener extendsthrough the first housing, the intermediate layer, and the secondhousing. A first nut coupled to the compression fastener is arrangedadjacent the first planar surface, and a second nut connected to thecompression fastener is arranged adjacent the second planar surface.

In addition to one or more of the features described above, or as analternative, in further embodiments the compression force applied to theintermediate layer by the first and second housings is controlled byadjusting one of the first nut and second nut.

According to another embodiment of the invention, a method of cleaning arotor blade spar is provided including inserting an assembly into ahollow interior of the spar. The assembly includes a first housing, asecond, housing, and an intermediate housing disposed between the firstand second housings. A seal is formed using the intermediate housing toseparate a closed interior surface of the spar from an open interiorsurface of the spar. A flow of fluid is generated into a cavity of thefirst housing and out of holes in the first housing such that the fluidflows toward the open interior surface of the spar without passing intothe closed interior surface of the spar.

In addition to one or more of the features described above, or as analternative, in further embodiments the inserting the assembly into thespar includes positioning the spar between an inboard end of the sparand a critical surface of the spar.

In addition to one or more of the features described above, or as analternative, in further embodiments forming the seal includescompressing the intermediate housing between the first housing and thesecond housing.

In addition to one or more of the features described above, or as analternative, in further embodiments the intermediate housing iscompressed by tightening a nut attached to a compression fastenerextending through the first housing, the intermediate housing, and thesecond housing.

In addition to one or more of the features described above, or as analternative, in further embodiments the flow of fluid into the cavity isgenerated by a pump operably coupled to a fluid supply, the fluid supplybeing one or air or coolant.

Technical effects include a rotor blade having minimal interior damageto flight critical surfaces.

BRIEF DESCRIPTION OF THE DRAWINGS

The subject matter, which is regarded as the invention, is particularlypointed out and distinctly claimed in the claims at the conclusion ofthe specification. The foregoing and other features, and advantages ofthe invention are apparent from the following detailed description takenin conjunction with the accompanying drawings in which:

FIG. 1 is a perspective view of an example of a rotary wing aircraft;

FIG. 2 is perspective view of a rotor blade assembly of a main rotorsystem of a rotary wing aircraft according to an embodiment of theinvention;

FIG. 3 is a perspective view of an assembly configured to preventforeign object damage during the manufacture of a rotor blade assemblyaccording to an embodiment of the invention;

FIG. 4 is a perspective view of the assembly according to an embodimentof the invention;

FIG. 5 is another perspective view of the assembly according to anembodiment of the invention;

FIG. 6 is a perspective view of the assembly arranged within a rotorblade spar according to an embodiment of the invention; and

FIG. 7 is a cross-sectional view of the rotor blade assembly of FIG. 2taken along lines L-L according to an embodiment of the invention.

The detailed description explains embodiments of the invention, togetherwith advantages and features, by way of example with reference to thedrawings.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 schematically illustrates a rotary wing aircraft 10 having a mainrotor assembly 12. The aircraft 10 includes an airframe 14 having anextended tail 16 which mounts a tail rotor system 18, such as ananti-torque system, a translational thrust system, a pusher propeller, arotor propulsion system, and the like. The main rotor assembly 12includes a plurality of rotor blade assemblies 22 mounted to a rotor hub20. The main rotor assembly 12 is driven about an axis of rotation Athrough a main gearbox (illustrated schematically at T) by one or moreengines E. Although a particular helicopter configuration is illustratedand described in the disclosed embodiment, other configurations and/ormachines, such as high speed compound rotary wing aircrafts withsupplemental translational thrust systems, dual contra-rotating, coaxialrotor system aircrafts, tilt-rotors and tilt-wing aircrafts, and fixedwing aircrafts, will also benefit from embodiments of the invention.

Referring now to the exemplary rotor blade assembly 22 illustrated inFIG. 2, a generally hollow, tubular spar 30 configured to couple to therotor hub 20 at an inboard end 32 extends over at least a portion of thelength of the rotor blade assembly 22. In one embodiment, the spar 30may extend to the blade tip 24 of the rotor blade assembly 22. Thecross-section of the spar 30 may vary in size and shape over the lengthof the spar 30 depending on the contour of the rotor blade assembly 22.The spar 30 is a structural member having a high torsional and axialstiffness and strength and, therefore, may be made from a high strengthmaterial, including but not limited to metal, graphite, fiberglass orsome combination thereof. While shown with tip 24 having swept geometry,it is understood that the tip 24 need not have a swept geometry in allembodiments of the invention.

During manufacturing of a rotor blade assembly 22 having a blade spar 30with a closed outboard end 34, foreign objects can become depositedinside the spar 30. By way of example, during drilling or machining ofone or more holes in the blade spar 30, metallic pieces of the spar 30could be deposited inside the spar 30 and need to be removed. Anassembly 40 configured to prevent foreign object damage is positionedwithin the blade spar 30 to remove such foreign objects according toaspects of the invention. The shown assembly 40 is removable withrespect to the spar 30 and is removed from the spar 30 after manufactureis completed, although the invention is not limited thereto.

Referring now to FIGS. 3-5 the assembly 40 is illustrated in moredetail. The assembly 40 includes a first hollow housing 42 having ashape similar to the cross-sectional shape of the spar 30 at someposition along its length. The first housing 42 may be formed from aplastic material, such as through an injection molding process forexample; however other suitable materials, such as steel or aluminum forexample, are within the scope of the invention. In the illustrated,non-limiting embodiment, the housing 42 is formed by a complementaryfirst portion 44 and second portion 46 having a similar size and shape.The first and second portion 44, 46 may include features, such as asnap-fit connection for example, configured to selectively couple thefirst and second portion 44, 46 to one another to form the first housing42. The first portion 44 is solid, and the second portion 46 has acavity 47.

An inlet port 48 is formed in a first planar surface 50 of the firsthousing 42, and extends through the first portion 44 to a second,opposite planar surface (not shown) of the first portion 44 so as to beopen to the cavity 47. A plurality of small openings 52 is also formedabout the periphery of the first surface 50 of the housing 42. Theopenings 52 may be equidistantly or variably spaced and may besubstantially identical or variable in size. In one embodiment, aportion of the small openings 52, such as near the inlet port 48 forexample, has a larger diameter than the remainder of the plurality ofsmall openings 52.

Arranged in contact with the second planar surface (not shown) of thefirst housing 42 is an intermediate layer 54 formed from a sponge-likematerial, such as rubber or foam for example. As illustrated, theintermediate layer 54 has a shape similar to the first housing 42.However, the intermediate layer 54 is configured to expand whencompressed, as shown in FIG. 3, so as to conform with the periphery ofthe interior surface 36 (FIG. 7) of the blade spar 30 and to close offthe cavity 47. While shown with the intermediate layer 54 forming abottom of the cavity 47, it is understood that in other aspects thecavity 47 could be completely contained within the first housing 42 suchthat the fluid does not pass from the second portion 46 to theintermediate layer 54. A second housing 56 having a shape substantiallysimilar to the first housing 42 and the intermediate layer 54 ispositioned adjacent the intermediate layer 54, opposite the firsthousing 42. The second housing 56 is generally formed from the samematerial as the first housing 42, and may be either solid or hollow.

At least one fastener 60 extends through a through hole 62 formed in thefirst housing 42, intermediate layer 54, and second housing 56 to affixthe components 42, 54, 56 to one another. In the illustratednon-limiting embodiment, a first fastener 60 is arranged near a firstside 41 of the assembly and a second, substantially identical fastener60 is arranged adjacent a second, opposite side 43 of the assembly 40. Acompression fastener 64 similarly extends through a through hole 66arranged near the middle of the assembly 40. The compression fastener 64may be substantially equal in length and/or diameter to the otherfasteners 60, or alternatively, may have a larger diameter and or lengthas shown. While three fasteners are shown by way of example, othernumbers of fasteners can be used in other aspects of the invention.

A first nut 70 is coupled to fasteners 60, 64 adjacent the first planarsurface 50 of the first housing 42. Similarly, a second nut 72 iscoupled to the fasteners 60, 64 adjacent the exposed planar surface 58of the second housing 56. In the illustrated, non-limiting embodiment, aplurality of recesses 74 are formed in the exposed planar surface 58adjacent each of the through holes 62, 66. The recesses 74 areconfigured to receive the second nut 72 connected to each fastener 60,64 such that the nuts 72 are substantially flush with the planar surface58 of the second housing 56. In another embodiment, the second nuts 72may be integrally formed with the second housing 56, such as by formingthreads in the portion of the through holes 62, 66 extending therethrough. The first nut 70 and second nut 72 coupled to the compressionfastener 64 are used to increase and decrease the compression forceapplied by the first and second housings 42, 56 on the intermediatelayer 54. When the compression force is increased, the intermediatelayer 54 expands so that a cross-section of the intermediate layer 54 islarger than a cross-section of the adjacent housings 42, 56.

Referring now to FIGS. 6 and 7, during manufacture of a rotor bladeassembly 22, the assembly 40 is positioned within the spar 30 such thatthe first planar surface 50 of the first housing 42 faces the open,inboard end 32 of the spar and the exposed planar surface 58 of thesecond housing 56 faces the closed, outboard end 34 of the spar 30. Inone embodiment, the assembly 40 is positioned at a distance betweenabout two feet and about three feet from the inboard end 32 of the spar30. When located at the desired position within the spar 30, the firstnut 70 coupled to the compression fastener 64 is adjusted until theintermediate layer 54 forms a seal with the interior surface 36 of thespar 30. A pump (illustrated schematically at P in FIG. 6), operablycoupled to a fluid supply, such as air or coolant for example, isconnected to the inlet port 48. The fluid is configured to flow throughthe inlet port 48 into the cavity 47 of the first housing 42, and outthrough the plurality of small openings 52. While not required in allaspects, the fluid can pass partially through the intermediate layer 54so as to clean or filter the fluid.

The reverse flow from the assembly 40 towards the open, inboard end 32of the spar 30 counters the flow of debris and particles into the spar30 without injecting fluid in the space between the closed, outboard end34 of the spar 30 and the assembly 40. By positioning the assembly 40between the closed end 34 and any interior surfaces 36 that are criticalto flight safety, the fluid is injected via the inlet port 48 to passthrough the first portion 44 of the housing 42 into the cavity 47. Thefluid is stored within the cavity 47, and when sufficient pressure hasbuilt up, the fluid exits the assembly 40 from the cavity 47 via theopenings 52 in the first housing 42 back towards the open, inboard end32 of the spar 30. Since the assembly 40 is disposed between the closedend 34 and the surface to be protected 36, the fluid passes over thesurface 36 such that surface characteristics of such critical surfaces36 are protected from possible damage during the manufacturing process.In addition, use of the assembly 40 during manufacture of the rotorblade assemblies 22 greatly reduces work costs and improves themanufacturing process. Although the assembly 40 is illustrated anddescribed herein within a blade spar 30, the assembly 40 may bepositioned within any object having a hollow interior, an open end, anda closed end, to prevent damage during manufacture thereof, such as forcleaning gas and/or water pipelines, perform plumbing maintenance, orthe like.

While the invention has been described in detail in connection with onlya limited number of embodiments, it should be readily understood thatthe invention is not limited to such disclosed embodiments. By way ofexample, the first housing 42 may be a single piece as opposed toseparate first and second portions 44, 46 as shown. Rather, theinvention can be modified to incorporate any number of variations,alterations, substitutions or equivalent arrangements not heretoforedescribed, but which are commensurate with the spirit and scope of theinvention. Additionally, while various embodiments of the invention havebeen described, it is to be understood that aspects of the invention mayinclude only some of the described embodiments. Accordingly, theinvention is not to be seen as limited by the foregoing description, butis only limited by the scope of the appended claims.

What is claimed is:
 1. An assembly configured to prevent damage to anobject during manufacture of the object, comprising: a first housinghaving a substantially hollow interior and an exposed first planarsurface, an inlet port being formed in the first planar surface, and aplurality of small openings being formed about a periphery of the firstplanar surface, such that the inlet port, the hollow interior, and theplurality of small openings form a flow path for a fluid through theassembly; a second housing substantially similar in shape and size tothe first housing, the second housing having an exposed second planarsurface; an intermediate layer arranged between the first housing andthe second housing, a cross-section of the intermediate layer beingconfigured to change shape in response to a compression force appliedthereto by the first housing and the second housing to form a sealseparating an exterior portion of the object exposed to the plurality ofsmall openings from an interior surface of the object.
 2. The assemblyaccording to claim 1, wherein the flow path is configured to counter aflow of debris into the interior surface of the object.
 3. The assemblyaccording to claim 1, wherein the inlet port is connected to a pumpoperably coupled to a fluid supply.
 4. The assembly according to claim3, wherein the fluid supply includes one of air or coolant.
 5. Theassembly according to claim 1, wherein the plurality of small openingsare equidistantly spaced about the periphery of the first planarsurface.
 6. The assembly according to claim 1, wherein a portion of theplurality of small openings have a diameter larger than a remainder ofthe plurality of small openings.
 7. The assembly according to claim 6,wherein the portion of small openings adjacent the inlet portion have adiameter larger than the remainder of the plurality of small openings.8. The assembly according to claim 1, further comprising at least onefastener extending through and being configured to affix the firsthousing, the intermediate layer, and the second housing to one another.9. The assembly according to claim 1, further comprising a compressionfastener extending through the first housing, the intermediate layer,and the second housing, a first nut coupled to the compression fastenerbeing arranged adjacent the first planar surface, and a second nutconnected to the compression fastener being arranged near the secondplanar surface.
 10. The assembly according to claim 9, wherein thecompression force applied to the intermediate layer by the first housingand the second housing is controlled by adjusting one or the first nutand second nut.